Oral Complications are not only a major cause of pain and suffering for patients undergoing marrow transplantation (BMT), but can also contribute to systemic complications and fatality. Many factors cause or influence the severity of BMT oral complications, including chemoradiotherapy conditioning regimens, oral infections, and acute and chronic GVHD. Little is known about which factors acting singly or in combination are most damaging to oral tissues; the clinical recognition and diagnosis of some complications is unclear, the types and frequency of risks associated with the presence of these complications has yet to be determined. There have been no reported studies on how acute GVHD is manifested in the mouth. Oral acute GVHD frequently goes undetected or is misdiagnosed which can result in delayed diagnosis, compromise overall patient management and lead to increased suffering and risk of other complications. Similar problems exist for oral toxicities resulting from chemoradiotherapy and from oral microbial colonization and infection. We will examine factors likely to influence the frequency and severity of oral complications following BMT. These will include; a) patient-related factors such as patient age, disease, previous therapy, pretransplant oral health, numbers and types of dental restorations and appliances, and oral habits (including smoking) and b) BMT-related factors such as the type and dosage of agents used in BMT conditioning regimens, the use of biological response modifiers, post-BMT immunosuppressive therapy, the rate of engraftment, oral microbial colonization and types of infections, including viral infections, and acute GVHD. The investigators will study these factors through a) the review of prior medical records and medical history, b) frequent detailed clinical examinations, and c) specific laboratory (pathology, microbiology, chemistry, etc.) data. They expect to: a) determine the contribution various risk factors make to the various oral complications observed; b) develop useful diagnostic criteria for diagnosing oral complications of BMT; and c) thus determine oral complication risk profiles for patients. Besides facilitating more expeditious diagnosis of oral complications, these studies will aid in the design of oral care protocols to more efficiently and effectively prevent and/or manage oral problems. They will also enhance understanding of how oral complications can cause or influence systemic complications following BMT.